Assisting the older driver - SWOV

Assisting the older driver
sensitive to ageing. Tests in these domains have been repeatedly found to
correlate with poor on‐road driving performance and crash involvement (see
e.g., Ball et al., 2006; Hoffman, McDowd, Atchley & Dubinsky, 2005; Wood,
2002).
Dynamic visual acuity and detection of movement
Dynamic visual acuity is the ability to resolve details of a moving target. Its
deterioration is probably attributable to the required oculomotor control
(Shinar & Schieber, 1991). The oculomotor system is also involved in
detection of movement. However, the decline in detection of movement with
increasing age appears to be mainly the result of age‐related changes to
neural mechanisms. Obviously, the ability to detect movement is very
important for safe driving, not only for being able to detect vehicles driving
on an intersecting road and to estimate their speed, but also for being able to
detect changes in the speed of vehicles in front, i.e., stopping, slowing down,
speeding up, and reversing (Holland, 2001; Shinar & Schieber, 1991).
Night‐time visual acuity and sensitivity to glare
Impaired night‐time visual acuity is the result of two age‐related changes
that reduce the amount of light reaching the retina: reduced pupil size and
yellowing of the lens (Olson, 1993). A consequence of reduced retinal
illumination is that sources must be of higher intensity to be seen at night
(e.g., Olson, 1993). Sensitivity to glare, which increases between the ages of
40 and 70, leads to a slower recovery from headlights and other reflecting
sources (Fozard et al. (1977) cited in Aizenberg & McKenzie, 1997).
Contrast sensitivity
As far as contrast sensitivity is concerned, older adults have more difficulties
detecting objects that are not outlined clearly or that do not stand out from
their background. Its deterioration is probably attributable to changes in the
eye itself as well as neural factors. Contrast sensitivity is – even more than
visual acuity – necessary for the perception of (the information on) traffic
signs. Besides this, contrast sensitivity is also believed to play a role in
distance perception and the estimation of the speed of moving objects
(Holland, 2001; Shinar & Schieber, 1991).
2.2.2. Cognitive functions
Age‐related declines in sensory functions such as vision and hearing have an
impact on the input the driver receives from other road users and from the
road environment (e.g., traffic signs and signals, road markings). To select
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